查看更多>>摘要：Convenient non-invasive flow monitoring would facilitate the operation and control in microfluidic chips,but is challenging due to the small space of microchannels and complex operation required in traditional optical methods.In this work,we propose a novel non-invasive strategy to probe microfluidic flows via streaming potential phenomenon.By sealing one side of the microchannel with a piece of hydrogel film,streaming potential inside the channel can be clearly detected by electrodes at outer surface of the hydrogel due to ion diffusion in the hydrogel.Flow is detected without sensors contacting with the internal liquid.Moreover,the electrodes shape like a tiny probe,which can move around mapping the flow distribution in a chip with the spatial resolution of 1 mm and flow rate detection limit of 3 μL·min-1.Bubbles inside the channels can also be detected,due to the fluctuation of streaming voltage when gas-liquid interface flows through the electrode,showing an easy and potential way for multi-functional flow monitoring in microflu-idic chips.
查看更多>>摘要：The reductive cross-coupling between C(aryl)-O and Si-Cl bonds is of much importance as a valuable strategy for the construction of C(aryl)-Si bonds but has remained a great challenge.Herein,we report a reductive cross-coupling of diaryl ethers and chlorosilanes via strong electrophilic C(aryl)-O and Si-Cl bonds cleavage by iron catalysis,which constitutes an efficient protocol for the synthesis of a range of functionalized arylsilanes.The combination of low cost FeCl2 as the precatalyst and iPrMgCl as the reductant shows high activity in the successive cleavage of unactivated C(aryl)-O bonds of diaryl ethers and strong electrophilic Si-Cl bonds of chlorosilanes,allowing their cross-coupling in a reductive fashion.The low-valent iron species generated in situ by reduction of FeCl2 withiPrMgCl was proposed,which prefers to initially cleavage the C(aryl)-O bond of diaryl ethers with the chelation help of an o-amide auxiliary.
查看更多>>摘要：A straightforward electrochemical reduction of benzo[b]thiophene 1,1-dioxides with HFIP as the hydrogen donor has been reported in an undivided cell under metal-free conditions.Moreover,the tolerance of various functional groups and scaled-up experiments showed the practicability and potential applications of this methodology.
查看更多>>摘要：Polyoxometalates modified with complex cations have attracted increasing attention because of the fascinating properties and the controllable structures.By adjusting the synthesis conditions,four new terpyridine complexes based hybrid POMs,[(TPY-H)CuCl]4[W10O32]-2DMF-2H2O(1),[(TPY-H)Cu(DMSO)(H2O)]2[W10O32]-2H2O(2),[(TPY-H)2Cu]2[W10O32]-6DMSO-8H2O(3)and[(TPY-Br)CuCl(DMSO)(H2O)]2[(TPY-Br)CuCl]2[W10O32]-2DMSO-4H2O(4),were prepared by using'one-pot'method.Sing-crystal X-ray diffraction anal-yses,infrared radiation,etc.,revealed the structural composition of compounds 1-4,which indicates that synthesis conditions have a directional regulatory effect on the compounds synthesis.Thioether oxidation catalytic reactions show 1-4 have good catalytic activi-ties,and powder X-ray diffraction and thermogravimetry analysis show 1-4 have superduper catalytic stability.Moreover,4 has bet-ter catalytic activity because of the different structure of terpyridine complexes.Therefore,a possible mechanism of dual-site catalysis by both cations and anions is proposed.
查看更多>>摘要：Transition metal-catalyzed carbometallation of unsaturated hydrocarbons constitutes one of the most efficient synthetic methodolo-gies for the construction of C-C bond.Recently,the incorporation of organometallic reagent with the CO gas as a nucleophilic acyl synthon could enable the acylmetallation reaction,which greatly increases the horizon of carbometallation chemistry.Herein,we re-port a nickel-catalyzed regiodivergent acylzincation of o-cyano cinnamate ester and o-cyano styrene,in which the cyano moiety intra-molecularly captures zinc intermediates to trigger the tandem cyclization process.This protocol features mild conditions,broad sub-strate scope and excellent functional group tolerance,thus affording a diverse array of highly functionalized carbocyclic compounds.
查看更多>>摘要：The total synthesis of majusculamide D(1)was achieved from commercially available materials.In addition,we synthesized eight an-alogues including three stereoisomers of majusculamide D that differ in the fatty acid chain.Six analogues including a simplified ana-logue 29 exhibited significant nanomolar-level IC50 values against Panc-1 cells in MTT assays.A preliminary SAR analysis indicated that the hydroxyl group at C1O and C2-C3 unsaturated double bond of majusculamide D were essential in maintaining the high activity against Panc-1 cells and the orientation of C40-Me and C42-Me groups was tolerable.
查看更多>>摘要：Mechanochromic polymers based on non-covalent changes have attracted much attention recently.Herein,we report the impact of inter/intramolecular hydrogen bonds on polymer mechanochromism from the excited state intramolecular proton transfer(ESIPT)process.PhMz-NH2-OH and PhMz=2A are designed and obtained by simple and high-yield synthesis,and are connected into polyure-thane and poly(methyl acrylate-co-2-ethylhexyl acrylate),respectively.In the initial state,the PhMz-NH2-OH@PU sample shows blue fluorescence from the excited enol form(E*)excitons,owing to intermolecular hydrogen bonds that interrupt the ESIPT reactions but the PhMz=2A@PMA-2-EA sample expresses cyan fluorescence belonging to the excited keto form(K*)emission,implying that the in-tramolecular hydrogen bonds matter.Furthermore,under stretching,external force can tune the emission of the PhMz=2A@PMA-2-EA sample from K*to E*state.Though external force can putatively still promote a bond rotation,ESIPT reactions remain equivalently interrupted in both the relaxed and stressed states in a hydrogen-bond donating environment.DFT calculation confirms the force-induced increase in dihedral angle for the transition of ESIPT-on/off.Thus,PhMz-NH2-OH@PU and PhMz=2A@PMA-2-EA showed disparate initial ESIPT states and further different responses/sensitivity to force.This study reports a novel and efficient strategy for enriching mechanochromic investigation and extending the applications of ESIPT reactions.
查看更多>>摘要：Binary polyantimony clusters,namely[Cu2Sb14]4-and[Ag2Sb14]4-,containing coinage metals,were successfully synthesized and characterized,in which two homoatomic Sb73-subunits are bridged by two coinage metals in η4∶η1 and η1∶η1 coordination modes,respectively.In[Cu2Sb14]4-,two bridging Cu ions and two Sb atoms form a planar rhombic unit,which was revealed to have antiaro-matic properties by theoretical calculations.Further electron structure and bonding analysis confirmed the presence of delocalized bonds in the rhombic unit and the metallophilic interaction between two formal M+ions.
查看更多>>摘要：Fine-tuning of the electron-deficient unit in A-DA1D-A typed small-molecule acceptors(SMAs)plays a crucial role in developing efficient SMAs for organic solar cells(OSCs).Here,we developed a SMA based on benzo[4,5]thieno[2,3-b]quinoxaline,designated as QW1,as well as three SMAs based on 1-methylindoline-2,3-dione,identified as QW2,QW3,and QW4.Compared with QW2,QW1 displays slightly blue-shifted absorption spectra and a lower LUMO energy level due to the stronger electron-withdrawing capability of BTQx in contrast to MDO.On the other hand,the introduction of a bromine atom in QW3 and QW4 causes a blue shift in absorp-tion and a reduction in the LUMO energy level compared to QW2.Density functional theory analysis reveals that QW1 exhibits the best molecular planarity,which endows QW1 with larger electron mobility and tighter molecular stacking.Consequently,PM6:QW1 device affords a better efficiency of 15.63％than those of the devices based on QW2(14.25％),QW3(13.21％)and QW4(15.03％).Moreover,the QW4-based device yields the highest open-circuit voltage of 0.933 V,and the PM6:L8-BO:QW4 ternary device realizes a PCE of 19.03％.Overall,our work demonstrates that regulation of electron-deficient central units is an effective strategy to improve the photovoltaic performance of the resulting A-DA1D-A SMAs.
查看更多>>摘要：The asymmetric hydrogenation of N-heteroarenes provides an efficient method for the synthesis of optically active cyclic secondary amines.In this paper,we described an asymmetric hydrogenation of phenanthridines using a chiral mono-alkene-derived borane.A variety of dihydrophenanthridines were furnished in high yields with up to 93％ee.The current catalytic system was very sensitive for the steric hindrance of phenanthridines.Bulky substituents at one phenyl group of phenanthridines were required to obtain the high enantioselectivity.But large substituents on the carbon of the C=N bonds would diminish the reactivity sharply.
万方数据
维普